1. Field of the Invention
This invention is directed toward an improved saw tooth for circular saws.
The invention is also directed toward an improved saw tooth assembly using the improved saw tooth.
2. Description of the Related Art Including Information Disclosed Under CFR xc2xa7xc2xa71.97-1.99
The improved saw tooth of the present invention is of the type used in circular saws, the circular saws being used in tree harvesting equipment. The saw tooth is also of the type that can be replaced on the blade of the circular saw when it becomes dull.
Replacing the saw teeth when they become dull can be expensive. To reduce the expense of replacing the teeth it is known to provide a saw tooth having several cutting edges. When one cutting edge becomes dull, the saw tooth is merely repositioned on the saw blade to present an unused cutting edge in the cutting position. Thus one tooth can be used two, or preferably four times, before it needs to be replaced. Thus the expense of replacing teeth is greatly reduced. Examples of such saw teeth, with multiple cutting edges, are shown in U.S. Pat. No. 4,932,447, issued Jun. 12, 1990, Armand J. Morin inventor; U.S. Pat. No. 5,058,477, issued Oct. 22, 1991, Charles D. MacLennan inventor; and U.S. Pat. No. 5,205,199, issued Apr. 27, 1993, Charles D. MacLennan inventor, by way of example. The known cutting teeth with four cutting edges are relatively expensive however. They usually employ curved cutting edges, as shown in U.S. Pat. Nos. 4,932,447 and 5,058,477, and thus their manufacture is relatively expensive. Even when the known teeth employ straight cutting edges, as shown in U.S. Pat. No. 5,205,199, the tooth is still relatively expensive to manufacture since the surfaces of the tooth forming all the cutting edges are quite numerous and complex.
It is the purpose of the present invention to provide an improved cutting tooth of the type with two or more cutting edges which tooth is relatively simple in construction and relatively inexpensive to produce compared to the known cutting teeth. In accordance with the present invention, the improved cutting tooth is provided with straight cutting edges which are easier to produce compared to curved cutting teeth known in the prior art. In addition, the joining surfaces providing the cutting edges are fewer in number and simpler than the surfaces used in the prior art.
In accordance with the present invention the improved saw tooth is a block-like, or generally parallelopiped, member having two opposed surfaces with each end of each surface having a cutting edge. The cutting edges on each surface are parallel to each other and are also parallel to the cutting edges on the other surface. The member has a central mounting hole extending between the surfaces, the axis of the hole transverse to the cutting edges.
The tooth is mounted on a mounting block on the rim of a circular saw blade by a bolt extending through the mounting hole in a manner to have one of the cutting edges on one of the surfaces in an outer, leading, cutting position. When this cutting edge becomes dull, the bolt is loosened; the tooth is rotated, relative to the mounting block, to place the other cutting edge on the same surface in the outer, leading cutting position; and the bolt is tightened. When this second cutting edge becomes dull, the bolt is removed, the tooth is reversed to place a cutting edge on the other surface in the cutting position, and the bolt is replaced and tightened. When the third edge becomes dull, the bolt is loosened, the tooth is rotated to place the other and last unused cutting edge on the other surface in the cutting position, and the bolt is tightened.
The invention is particularly directed toward a saw tooth having top and bottom surfaces; side surfaces; and front and back surfaces. Each front and back surface join the top and bottom surfaces at four parallel edge locations. Cutting edges are provided at at least two of these edge locations by having the front/back surfaces at these edge locations extend inwardly from the edge locations toward the other of the front/back surfaces. The cutting edges are parallel to each other.
The invention is also particularly directed toward a saw tooth assembly having; a saw tooth with top and bottom surfaces; side surfaces; and front and back surfaces. The front and back surfaces join the top and bottom surfaces at four parallel edge locations. Cutting edges are provided at at least two of these edge locations by having the front/back surfaces at these edge locations extend inwardly from the edge locations toward the other of the front/back surfaces. The cutting edges are parallel to each other. The assembly includes a mounting block adapted to mounted on the rim of a circular saw blade. Cooperating mounting surfaces on the mounting block and on the front and back surfaces of the saw tooth locate any one of the four cutting edges in cutting position when the saw tooth is detachably mounted on the block. A bolt detachably connects the tooth to the block with the mounting surface on the block abutting one of the mounting surfaces on the front or back surfaces of the tooth.